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Topic: How quickly to skunk? (Read 1661 times)

I just got up this morning and noticed that I left the florescent light in the cellar on last night. I'm usually fairly careful about covering my beers, even down there. I was less careful with this latest brew. Most are in brown bottles, but I do have some in green 75 cl bottles that I was planning to give away as gifts. Should I start shopping for other gifts?

Supposedly it is an instantaneous reaction. Personally, I'm not convinced. I tend to believe (without proof), the reactions are occurring, but the breaking point between perceivable levels of mercaptans and imperceptible levels is the point which seems instantaneous. Why do I think this...beers can skunk in green bottles sitting in a cooler case, one day you purchase a sixer of beer and everything is fine, a few days later another sixer from the same cooler is skunk city. That makes me think prolonged exposure builds the byproducts of the reaction until they are perceivable. Sitting a glass of beer in direct sunlight can seem to drive the reaction extremely quickly to a perceivable level of mercaptans.

I have done some professional lab research on this topic. (Sorry, I can't reveal who I was working for, or who was paying for it, but I can talk about the results. Don't ask.) I will add the caveat that we didn't study flourescent light, just sunlight. We could not find a predictable time threshold for the reaction. It is definitely based on the intensity of the light source, as well as the temperature. On a bright day at summer-time A/C room temperature, skunking could happen effectively instantaneously, but more often it takes an hour or more. Every beer (in a green bottle, that is) was skunked to flavor thresholds in less than two hours. They were skunked to instrumentation thresholds in minutes. Brown bottles doubled the time period. Double a few minutes is only a few more minutes. A bottle taken out of the refrigerator did not exceed flavor thresholds unless it was exposed long enough to warm to room temperature. We also only looked at one mass market lager, one I would not call bitter. I don't know the effect we would get with differing bitterness levels.

Elevated temps (e.g., during unrefrigerated transport on cargo containers/cargo ships) may cause more than one flaw in the green bottled import beer to occur. Sometimes when I crack open one of those green bottle imports (e.g., Heineken), I sense there's skunking as well as some oxidation. Blech!